52 GRAY SUBSTANCE OF THE TRAPEZIUM, 



posterior and postero-lateral parts of the main nucleus as well as the outer net- 

 work.^ 



At the apex, close to the entrance of the anterior division of the root, a group of 

 cells is found, Avhich are stellate or pyriform in shape and are quite large ; they are 

 connected partly with the anterior division of the root, and partly with numerous 

 bundles of radiating fibres which pass from the vicinity of the apex into the caput 

 cornu. All along the anterior border of the nucleus a beautiful fringe of very 

 numerous wavy fibres is seen, passing out into the anterior and antero-lateral columns, 

 derived apparently in part from the deeper lying regions of the nucleus, as well as 

 from the cells along the antero-lateral border. 



Stilling" has described a small nucleus in connection with the posterior root of 

 the auditory, which he seems to consider analogous to the spinal ganglia attached 

 to the posterior roots. It is situated at first on the outer side of the great bundle 

 of fibres constituting the posterior root of the auditory (Plate XIV, Fig. 9'*, z), and 

 consists of very small cells, which are continued upwards in nearly the same locality 

 until the auditory nerve finally disappears (Figs. 10", 12", 16"). 



In Fig. 10" this group is seen situated among the arciform fibres, just behind the 

 auditory root; in Plate XVI, Fig. 12", it occupies a similar position in the project- 

 ing mass, which represents the upward extension of the posterior root, though now 

 mainly consisting of the broad band of arciform fibres constituting the boundary 

 of the trapezium or commencement of the pons Varolii. This little group can 

 often be traced backwards towards the group situated in the posterior part of the 

 auditory nucleus, seen (Fig. 12") to be in evident connection with the flocculus, and 

 I have consequently been inclined to consider the little nucleus in question, rather 

 as a rudimentary fold of the cerebellum, which it strongly resembles, than as a 

 specific ganglion on the posterior auditory root ; this resemblance is especially striking 

 in the cat, a continuation of the flocculus being apparently folded down along the 

 auditory root (Plate IX, Figs. 35, 36). 



Foville,^ as is well known, has described a connection between the auditory nerve 

 and the flocculus, and at the same time to such an extent with the cerebellum that 

 he has called the auditory a cerebellar nerve (nerf cer^beUeux). The connections 

 between the posterior portion of the auditory nucleus and the cerebellum are very 

 striking and complicated, and merit more attention than I have been able to bestow 

 upon them. In order to fully understand the meaning of the diff'erent bundles of 

 fibres which everywhere stream out from the back of the auditory nucleus, it would 

 be necessary to carefully trace them into the cerebellum, and to understand very 

 fully their destination within this organ ; this of course does not come within the limits 

 of the present paper, but I shall briefly notice a few points which are most easily 

 made out. 



'■ lu the medulla of the cat I have been able to count over 60 large cells in a field measuring about 

 Jij of an inch in diameter, and as this was done with a x\ objective without changing the focal adjust- 

 ment, only those on the same plane were counted. 



^ Bau des Hirnknotens. Jena, 1846, 28. 



' Traite eomplet de P Anatomic et Physiologic du Systcme Nerveu.x Cerebro-Spinal, Paris, 1844, 503. 



